There is a growing body of evidence that a network of cytokines is involved in the growth, progression, and dissemination of multiple myeloma. Some are actually produced by the malignant plasma cells including interleulkin-1 beta (IL-1β) tumor necrosis factor-alpha (TNF-α), vascular endothelial growth factor (VEGF), and a functionally active truncated version of macrophage colony-stimulating factor (M-CSF). These and other cytokines act as mediators of tumor cell growth, survival, migration, and development of drug resistance.